276 



H. H. WILDER, 



Gegenbaur : 



The complete separation of the 

 laryngeal cartilages from the rest 

 of the branchial system finds its 

 parallel in the formation of the 

 Os thyroideum. 



By the discovery of the identity 

 of the epiglottis with the 4th 

 branchial arch , every branchial 

 element is thus seen to become 

 modified sooner or later as a 

 laryngeal cartilage. 



The Cartilago lateralis appears 

 in the larval salamander as a 

 single piece (ein einheitliches 

 Knorpelstück) which extends along 

 the sides of the trachea and reaches 

 to the lungs. In this piece there 

 develop five pairs of centres, 

 histologically different from the 

 remaining mass. Of these centers, 

 the first pair becomes the ary- 

 taenoids , posterior to which a 

 lateral piece develops applied to 

 the sides of the trachea. (Whether 

 this last comes from the second 

 of the pairs of centers, or from a 

 fusion of all the remaining ones, 

 is not indicated). 



Wilder (1892): 



Other branchial arches have 

 been shown to enter the service 

 of the larynx, e. g. the Mammalian 

 thyroid from the 2"^ and Sr«' 

 (Dubois). 



The original Cartilago lateralis 

 gives rise to the arytaenoids alone. 

 The "tracheal elements" are a new 

 formation, arising directly from 

 the connective tissue. This de- 

 velopment "can be distinctly seen 

 at a time when the hyaline ary- 

 taenoids are already well de- 

 veloped ". 



The above results I have given in a tabulated form for the 

 sake of comparison and in my own words for the sake of brevity, 

 hoping that thereby I have not in any way misinterpreted the sense 

 of the original. 



I may state here that my present beliefs resulting from farther 

 research are somewhat at variance with my own conclusions of 1892 

 as well as with those of Gegenbaur, and that these points of dif- 

 ference will be noted in the body of the work and receive full atten- 

 tion in the concluding summary. 



As the majority of the work has consisted of purely anatomical 

 preparation, no especial methods have been used. I have found 

 great benefit, however, in the use of Methyl- blue in the demonstration 

 of cartilage. For this purpose a few drops of this staining fluid are 



